1. Field of the Invention
The invention relates generally to the field of aligning an objective lens within a cylinder and more particularly to alignment means for the objective lens.
2. Brief Description of the Prior Art
Prior laser light pens captured the objective lens between two rings, substantially as shown in FIG. 1. Precision alignment techniques were used to position the objective 10 relative to the laser light source at 12. This included movement of the objective left to right in the figure. The spring 14 in the figure held the lens in position while a laser welder welded rings 16 and 17 in place.
A problem was presented by welding the rings in place. The body 18 holding the objective lenses is composed of a material such as a polycarbonate. The body 20 of the light pen is composed of a metal such as aluminum. The coefficients of thermal expansion of the two materials are different. When the light pen heats up during operation, this differential in coefficients causes warping of the objective lense body 18. This in turn causes either rotational or longitudinal misalignment of the objective lenses themselves. Further, the warping can cause the lenses to become loose and misoriented relative to the optical axis of the pen.
Another problem with the fixed ring system is that on mechanical shock, there is no cushioning effect, thus decreasing the tolerable level of shock.
A third problem involved the necessary tolerance between the objective body and the pen body. This tolerance allowed radial movement relative to the optical axis on thermal expansion or shock.